Glass formation in the Al<Subscript>2</Subscript>(SO<Subscript>4</Subscript>)<Subscript>3</Subscript>-Al(NO<Subscript>3</Subscript>)<Subscript>3</Subscript>-H<Subscript>2</Subscript>O system

Glass formation boundaries in the Al₂(SO₄)₃-Al(NO₃)₃-H₂O system were determined. IR spectra were studied. Schemes of structural rearrangements within the boundaries of a second glass formation region in the Al(NO₃)₃-H₂O binary subsystem are suggested. A structure is suggested for glassy Al(NO₃)₃H₂O.     

Interactions in the system Mn(NO<Subscript>3</Subscript>)<Subscript>2</Subscript>-HCONH<Subscript>2</Subscript>-H<Subscript>2</Subscript>O

Solubilities and solid phases in the system Mn(NO₃)₂-HCONH₂-H₂O were studied by an isothermal method at 25°C. The congruently saturating compound Mn(NO₃)₂ · 2HCONH₂ · 2H₂O was isolated; the concentration conditions for its crystallization in the system were determined. The solid phases of the system were characterized by physicochemical methods (X-ray powder diffraction, differential thermal analysis, IR spectroscopy, and crystal-optical analysis).     

Glass formation in the Al(IO<Subscript>3</Subscript>)<Subscript>3</Subscript>-Al<Subscript>2</Subscript>(SO<Subscript>4</Subscript>)<Subscript>3</Subscript>-HIO<Subscript>3</Subscript>-H<Subscript>2</Subscript>O system

On the basis of experimental data obtained in the study of glass-formation boundaries in the Al₂(SO₄)₃-HIO₃-H₂O, Al(IO₃)₃-Al₂(SO₄)₃-H₂O, and Al(IO₃)₃-HIO₃-H₂O systems and using geometrical analysis, we predict the positions of glass-formation boundaries in the Al(IO₃)₃-Al₂(SO₄)₃-HIO₃-H₂O four-component system along 60, 40, and 25 wt % H₂O sections.     

Phase formation in the ZrO(NO<Subscript>3</Subscript>)<Subscript>2</Subscript>-H<Subscript>3</Subscript>PO<Subscript>4</Subscript>-CsF-H<Subscript>2</Subscript>O system at low concentration of the phosphorus-containing component

The ZrO(NO₃)₂-H₃PO₄-CsF-H₂O system was studied at 20°C along the section at a molar ratio of PO₄³⁻/Zr = 0.5 (which is of the greatest interest in the context of phase formation) at ZrO₂ concentrations in the initial solutions of 2–14 wt % and molar ratios of CsF: Zr = 1−6. The following compounds were isolated for the first time: crystalline fluorophosphates CsZrF₂PO₄ · H₂O, amorphous oxofluorophosphate Cs₂Zr₃O₂F₄(PO₄)₂ · 3H₂O, and amorphous oxofluorophosphate nitrate CsZr₃O_1.25F₄(PO₄)₂(NO₃)_0.5 · 4.5H₂O. The compound Cs₃Zr₃O_1.5F₆(PO₄)₂ · 3H₂O was also isolated, which forms in a crystalline or glassy form, depending on conditions. The formation of the following new compounds was established: Cs₂Zr₃O_1.5F₅(PO₄)₂ · 2H₂O, Cs₂Zr₃F₂(PO₄)₄ · 4.5H₂O, and Zr₃O₄(PO₄)_1.33 · 6H₂O, which crystallize only in a mixture with known phases. All the compounds were studied by X-ray powder diffraction, crystal-optical, thermal, and IR spectroscopic analyses.     

Photochemical properties of mixed-ligand europium compounds of Eu(C<Subscript>10</Subscript>H<Subscript>11</Subscript>F<Subscript>7</Subscript>O<Subscript>2</Subscript>)<Subscript>3</Subscript>D composition

The intensively luminescing mixed-ligand europium compounds were synthesized of the composition Eu(C₁₀H₁₁F₇O₂)₃D, where C₁₀H₁₁F₇O₂ is heptafluorodimethyloctanedione, D is either 1,10-phenanthroline (C₁₂H₈N₂), triphenylphosphine oxide (C₁₈H₁₅PO), hexamethylphosphoramide (C₆H₁₈N₃PO), benzotriazole (C₆H₅N₃), or phenylguanidine [(C₆H₅NH)₂ =NH]. The luminescent properties of europium compounds in the crystalline state and in a polymer matrix of high-pressure polyethylene (HPPE) and polyvinyl chloride (PVC) and kinetics of the luminescence intensity decay under UV radiation were studied. The most photo-resistant in HDPE and PVC was found to be Eu(C₁₀H₁₁F₇O₂)₃Ph₃PO.     

Thermal Decomposition of the System CO(NH<Subscript>2</Subscript>)<Subscript>2</Subscript>-H<Subscript>3</Subscript>PO<Subscript>4</Subscript> in the Presence of Nitrate Compounds

Chemical, derivatographic, IR spectral, and X-ray diffraction analyses were used to study thermal transformations in the system CO(NH₂)₂-H₃PO₄ and in the same system with addition of KNO₃, CsNO₃, LiNO₃ · 3H₂O, and NH₄NO₃ salts in the temperature range 20–600°C. The influence of the chosen nitrate compounds on the process of reorganization of the constituent ingredients, evolution of nitrogen into the gas phase, yield of the solid residue, and preservation of nitrogen and phosphorus was revealed.     

K<Subscript>2</Subscript>SO<Subscript>4</Subscript>-K<Subscript>2</Subscript>HPO<Subscript>4</Subscript>-H<Subscript>2</Subscript>O phase diagram in the region of heterogeneous supercritical fluids

Our experimental study of phase equilibria in the K₂SO₄-K₂HPO₄-H₂O system at temperatures up to 500°C and pressures up to 100 MPa was directed to determine the sequence of phase transformations that generate heterogeneous supercritical fluids whose existence region propagates from the K₂SO₄-K₂HPO₄-H₂O subsystem into the ternary system. We found that supercritical fluids become heterogeneous as a result of addition of K₂HPO₄ starting with l ₁-l ₂ critical phenomena in saturated solutions, with the attendant amalgamation of the stable immiscibility region that propagates from the K₂HPO₄-H₂O system and the metastable liquid-liquid phase separation that originates from the K₂SO₄-H₂O system. Our experimental results and the topological analysis of phase equilibria in the vicinity of the critical point of water gave us the full scenario of the phase behavior of the title ternary system in the region of the subcritical and supercritical parameters of state.     

Glass formation in the system Al(IO<Subscript>3</Subscript>)<Subscript>3</Subscript>-HIO<Subscript>3</Subscript>-H<Subscript>2</Subscript>O

Glass-formation features in the system Al(IO₃)₃-HIO₃-H₂O are discussed, and the boundaries of the glass field are determined.     

Preparation,Thermal Behaviour,and Crystal Structure of MgAl<Subscript>2</Subscript>F<Subscript>8</Subscript>(H<Subscript>2</Subscript>O)<Subscript>2</Subscript>

Summary.  Single crystals of MgAl₂F₈(H₂O)₂ have been obtained under hydrothermal conditions (250°C, 14 d) from a starting mixture of AlF₃ and MgAlF₅(H₂O)₂ in a 5% (w/w) HF solution. The crystal structure has been determined and refined from single crystal data (Fmmm (#69), Z = 4, a = 7.2691(7), b = 7.0954(16), c = 12.452(2) ?, 281 structure factors, 27 parameters, R(F ² > 2σ (F ²)) = 0.0282, wR(F ² all) = 0.0885). The obtained crystals were systematically twinned according to (010/100/001) as twinning matrix, reflecting the pseudo-tetragonal metric. The crystal structure is composed of perowskite-type layers built of corner sharing AlF₆ octahedra with an overall composition of AlF₄ ⁻ which are connected via common fluorine atoms of [MgF_4/2(H₂O)_2/1] octahedra. Group-subgroup relations of MgAl₂F₈(H₂O)₂ to WO₃(H₂O)_0.33 and to other M(II)M(III)₂ F₈(H₂O)₂ structures are briefly discussed. Above 570°C, MgAl₂F₈(H₂O)₂ decomposes under elimination of water into α-AlF₃, β-AlF₃, and MgF₂. Received October 29, 2001. Accepted (revised) December 6, 2001     

Physicochemical properties of KOH-H<Subscript>2</Subscript>O<Subscript>2</Subscript>-H<Subscript>2</Subscript>O solutions

Density, viscosity, and surface tension of KOH-H₂O₂-H₂O solutions used to synthesize potassium superoxide in sprayer apparatus were studied with various relative amounts of the components in the temperature range 0–30°C. Analytical dependences of the above-mentioned quantities on temperature and solvent (water) content of the system were found.     

Behavior of silver sulfide in the system Ag<Subscript>2</Subscript>S-Fe(NO<Subscript>3</Subscript>)<Subscript>3</Subscript>-HNO<Subscript>3</Subscript>-H<Subscript>2</Subscript>O

Behavior of silver sulfide in the system Ag₂S-Fe(NO₃)₃-HNO₃-H₂O was studied at 25, 55, and 80°C using the method of the simplex-lattice experiment design. The quantitative dependences of Ag₂S oxidation on the concentrations of the acid and Fe³⁺ were determined. The isoconcentration diagrams were obtained.     

Phase equilibria and heterogenization of supercritical fluids in the K<Subscript>2</Subscript>SO<Subscript>4</Subscript>-K<Subscript>2</Subscript>CO<Subscript>3</Subscript>-H<Subscript>2</Subscript>O system

This experimental study of phase equilibria in the K₂SO₄-K₂CO₃-H₂O system at 385–500°C and pressures up to 100 MPa is directed to determine the sequence of phase transformations that generate heterogeneous supercritical fluids from the homogeneous one; the homogeneous supercritical region spreads into the ternary system from the K₂SO₄-H₂O subsystem. We found that heterogenization of supercritical fluid upon addition of K₂CO₃ starts with l₁=l₂ critical phenomena in solid saturated solutions and is attended by amalgamation of the stable immiscibility region that spreads from the K₂CO₃-H₂O system with the metastable immiscibility region that originates from the K₂SO₄-H₂O system. Our experimental results and the topological analysis of phase equilibria at temperatures above the critical point of water gave us the full scenario of the phase behavior of the title ternary system in the regions of fluid equilibria, g=l and l₁=l₂ critical phenomena, and liquid-liquid phase separation in two-, three-, and four-phase equilibria.     

The decomposition of gaseous products of the chemical transport reaction between H<Subscript>2</Subscript>O<Subscript>2</Subscript> and ZnO on the surface of silica gel

The decomposition of gaseous products of the chemical transport reaction that occurs in the interaction between H₂O₂ vapor and ZnO was studied on the surface of silica gel. At the initial stage of the decomposition of the intermediate complex formed in the chemical transport reaction between H₂O₂ and ZnO, the specific surface area of the sorbent increases noticeably. The pore size distribution maximum simultaneously shifts toward smaller values. The opposite effect is observed as the time of holding silica gel in a flow of gaseous products of the chemical transport reaction between H₂O₂ and ZnO increases. The treatment of the silica sorbent by the intermediate complex formed in the reaction between H₂O₂ and ZnO substantially influences the fractal dimension of its surface.     

Tin trifluoroacetylacetonate [Sn(C<Subscript>5</Subscript>H<Subscript>4</Subscript>O<Subscript>2</Subscript>F<Subscript>3</Subscript>)<Subscript>2</Subscript>] as a precursor of tin dioxide in APCVD process

A new method of synthesis of volatile complex, tin trifluoroacetylacetonate [Sn(C₅H₄O₂F₃)₂], was proposed. The prepared compound was identified by IR spectroscopy, CH analysis, X-ray powder diffraction, and DTA/TGA, the composition was confirmed by MALDI-TOF mass spectrometry, crystal structure was established. Thin films of tin dioxide on silicon were obtained by atmospheric pressure chemical vapor deposition using [Sn(C₅H₄O₂F₃)₂] as a precursor. The morphology and composition of the films were studied by scanning electron microscopy, EDX elemental analysis, and X-ray powder diffraction. Surface resistance and light transmission in visible and near IR region were studied.     

Phase equilibrium in the system RbCl-EuCl<Subscript>3</Subscript>-HCl(13.44, 22.75%)-H<Subscript>2</Subscript>O at 298.15 K

Solubility of the quaternary system RbCl-EuCl₃-HCl(13.44, 22.75%)-H₂O at 298.15 K was determined and corresponding equilibrium diagrams were constructed. The quaternary system is simple, and consists of two equilibrium solid phases RbCl and EuCl₃ · 6H₂O. The composition of double saturation point (average) is 13.29% HCl, 16.18% RbCl, and 18.72% EuCl₃ for the RbCl-EuCl₃-HCl(13.44%)-H₂O quaternary system, and 22.44% HCl, 15.59% RbCl, and 6.26% EuCl₃ for the RbCl-EuCl₃-HCl (22.75%)-H₂O quaternary system.     

Structural and thermal studies on the solid products in the system MnSeO<Subscript>3</Subscript>-SeO<Subscript>2</Subscript>-H<Subscript>2</Subscript>O

The solubility of MnSeO₃-SeO₂-H₂O system was studied in the temperature region 25–300°C. The compounds of the three-component system were identified by the Schreinemaker’s method. The phase diagram of manganese(II) selenites was drawn and the crystallization fields for the different phases were determined. Depending on the conditions for hydrothermal synthesis, MnSeO₃·H₂O, MnSeO₃·3/4H₂O, MnSeO₃·l/3H₂O and MnSe₂O₅ were obtained. The different phases were proven and characterized by chemical, powder X-ray diffraction and thermal analyses, as well as IR spectroscopy. The kinetics of dehydration and decomposition of MnSeO₃·H₂O was studied under non-isothermal heating. Based on 4 calculation procedures and 27 kinetic equations, the values of activation energy and pre-exponential factor in Arrhenius equation were calculated for both processes.     

Energetic aspects in description of metal—hydrogen—boron bonds in (B<Subscript>10</Subscript>H<Subscript>14</Subscript>)<Subscript>2</Subscript>Pt and (B<Subscript>8</Subscript>C<Subscript>12</Subscript>H<Subscript>14</Subscript>)<Subscript>2</Subscript>Pt complexes

The energies of formation of platinum complexes with borohydrides B₁₀H₁₄ and B₁₀H ₁₄ ^2- or carboranes B₈C₂H₁₄ and B₈C₂H ₁₄ ^2- were considered in terms of the structure—thermodynamics model. The thermodynamic stability of these complexes was substantiated.Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 2, 2005, pp. 149–152. Original Russian Text Copyright © 2005 by Ionov, Kuznetsov.     

Kinetics and mechanism of decomposition of peroxide compounds in the liquid phase of the KOH-H<Subscript>2</Subscript>O<Subscript>2</Subscript>-H<Subscript>2</Subscript>O system in vessels made of various materials

Decomposition kinetics of peroxide compounds in the liquid phase of the system KOH-H₂O₂-H₂O at an initial hydrogen peroxide concentration of about 14.5 M and pH 12.7 in vessels made of Pyrex glass, polyethylene terephthalate, and 12Kh18N10T steel was studied in the temperature range from ?10 to +50°C. The main kinetic parameters of the processes under study were determined. The influence exerted by the material of the reaction vessel on the kinetics and mechanism of decomposition of peroxide compounds in the liquid phase of the system under study were determined.     

The saturated hydrides of C<Subscript>60</Subscript>:F<Subscript>5</Subscript>F<Subscript>6</Subscript> PK F<Subscript>5</Subscript>F<Subscript>7</Subscript> isomers

The carbon cages composed of pentagons and heptagons (F₅F₇ isomers) are the analogs of fullerenes composed of pentagons and hexagons (F₅F₆ isomers). To provide insight into the structures and stability of the hydrides of F₅F₆ and F₅F₇ isomers, systematical density functional theory calculations are performed on all the 1,812 F₅F₆–C₆₀H₆₀ and 56 F₅F₇–C₆₀H₆₀. The calculated results demonstrate that the isomer with lowest/highest energy has most/fewest fused pentagons for both F₅F₆ and F₅F₇ hydrides and the stability of these hydrides increase with the number of fused pentagons roughly. The lowest energy F₅F₆–C₆₀H₆₀ and F₅F₇–C₆₀H₆₀ are 237.1 and 152.5 kcal/mol lower in energy than the isolated pentagon rule (IPR) C₆₀H₆₀, respectively; however, these two parent cages are 529.6 and 660.0 kcal/mol higher in energy than the IPR C₆₀. The calculations suggest that heptagon-containing cages, not only those violating the IPR can be the candidate cages for fullerene derivatives and the possible repulsion between the added atoms may play an important role in determining the structures and stability of the hydrides of carbon cages.     

Study of the crystallization fields of cobalt(II) slenites in the system CoSeO<Subscript>3</Subscript>-SeO<Subscript>2</Subscript>-H<Subscript>2</Subscript>O

Summary The solubility of CoSeO₃-SeO₂-H₂O system in the temperature region 298-573 K was studied. The phase diagram of cobalt(II)selenites was drawn and the crystallization fields for the different phases were determined. Depending on the conditions for hydrothermal synthesis, CoSeO₃×2H₂O, α-CoSeO₃×1/3H₂O, β-CoSeO₃×1/3H₂O, CoSeO₃, Co(HSeO₃)₂×2H₂O and CoSe₂O₅ were obtained. The different phases were proved and characterized by chemical and X-ray analyses, as well as IR spectroscopy.